This invention relates to tufting machines and more particularly to apparatus for reducing or eliminating oil leakage from the push rod housings of tufting machines especially those operating at very high speeds.
In a tufting machine a multiplicity of needles are reciprocably driven to penetrate a moving backing material to form loops of yarn beneath the backing material, the needles cooperating with loopers or hooks which seize the loops, and either release the loops or hold them until cut, thereby providing either loop or cut tufts protruding from the backing material. The needles are supported by a bar which is driven by a number of push rods journalled in push rod housings in the head of the machine and reciprocably driven by drive means carried in the head of the machine. To provide lubrication and cooling of the push rods and the drive means the frame of the machine includes an oil sump and pump means for directing lubricating oil onto the moving parts.
Sealing the reciprocating push rods in the housing against oil leakage from the push rod housings onto the tufted fabric has always been a problem in the tufting art. Consequently, a water soluble lubricant was developed and has been used for some time. Until relatively recently this lubricant was washed from the tufted fabric in carpet manufacturing facilities during the dying process which utilized a dying bath including detergents which acted to dissolve and wash the lubricant from the fabric during the dying operation. However, recently a more cost effective and energy efficient dying process using foam was developed and is now substantially universally used. Thus, any lubricant that leaks onto the fabric remains and the fabric must be discarded or sold as seconds.
In addition to the reemergence of lubricant leakage as a problem because of the change in dying process, recent tufting machines are operating at substantially higher speeds resulting in a greater leakage of lubricant from the push rod housings. The presently known seals have not been effective against prevention of leakage from the push rod housings. Most of the seals, if effective at all, are only effective for a few hundred thousand cycles. Since a tufting machine such as that illustrated in copending U.S. application Ser. No. 540,365 which is a continuation of application Ser. No. 407,753 operates at speeds in excess of 1200 rpm, the push rods undergo over a million and a half cycles in a 24 hour period resulting in rapid deterioration and failure of the seals and substantial leakage onto the fabric.
Additionally, as the speed of the tufting machine increases, and thus the speed at which the push rods are reciprocating increases, the frictional heat generated causes the push rods to become hot. Consequently, to reduce the heating of the push rods it is desired that additional lubricant be supplied to cool the push rods. This compounds the leakage problems since additional lubrication of the push rods has resulted in additional leakage from the push rod housings.